The present invention relates generally to separating nested cups and feeding the separated cups for further processing, and more particularly, is directed to a high speed machine for separating nested foam cups and feeding the cups for further processing using a venturi air pressure arrangement.
Printing machines which print on cylindrical or frusto-conical shaped drinking cups made of a material sold under the trademark “STYROFOAM” are known in the art. Hereinafter, reference to a foam material is intended to encompass the material sold under the trademark “STYROFOAM.”
Generally, in machines of this type, there is a rotatable printing blanket cylinder having a plurality of rubber printing blankets mounted thereon which sequentially pass by different inking assemblies. Each inking assembly has a different color which can be applied to a printing plate associated with it and the printing plate transfers ink to each blanket. When the printing blanket has passed the last inking assembly, all of the desired colors have been placed thereon to form a composite color image.
A rotatable cylinder is also provided and has different mandrels thereon which are each supplied sequentially from a feed assembly with a cup to be printed. As the cup on each respective mandrel passes in front of the printing blanket, it is rotated so that an entire image is printed on the external surface of the cup. The cup is then removed at a subsequent take-off location.
Specifically, each cup is held on a mandrel by vacuum pressure. The cups are stacked or nested, and are supplied one at a time from a tube or track to the mandrel at the infeed station. However, problems result when the cups are made of a foam material. Conventionally, there are mechanical means with air jet assists for moving the cups onto the mandrel. For example, there are rotating guides or stops on diametrically opposite sides of the nested cups, each of which has a finger or arcuate cam which is adapted to restrain the forward end of the forwardmost cup. When a shaft on which the rotating guides are mounted, is rotated, such that the fingers are positioned in blocking relation in front of the forwardmost cup, the forwardmost cup is restrained. However, when the shaft is rotated 180 degrees, the fingers are moved out of the blocking relationship so that the forwardmost cup is free and can be sucked onto the mandrel by vacuum pressure applied through the central opening of the mandrel and by air jet assists.
The problem with the prior art is that, because the cups are made of foam material, that is a material sold under the trademark “STYROFOAM,” they tend to stick together, and it is difficult to separate the cups. As a result, it is impossible to provide a high speed operation.
In accordance with the prior art, a small number of air jets are provided which direct compressed air to the space between the first or forwardmost cup and the second or next cup to aid in separating these cups. In addition, other air jets are provided which are directed in front of the first cup in the opposite direction toward the mandrel to create a suction or vacuum for pulling the first cup out and onto the mandrel. However, even with these air jets, separation of the cups becomes difficult.
The inventor herein has discovered that the reason it is difficult to separate the cups, even with such air jets, is because there only are a discrete number of air jets, for example, between four and eight air jets. As a result, the air from an air jet travels in the gap between the first and second cups, on one side of first cup, and exits in the gap on another side of the first cup. However, as the air flow exits the gap between the first and second cups, it creates a vacuum which tends to pull the cups together, thereby defeating the purpose of the air flow.